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SN75DP130: SN75DP130 redriver Link Training fail at low temperature situation (0°C)

Feng bin Su
Expert 8790 points
Part Number: SN75DP130

Hi team,

My customer has designed their product with our DP redriver (SN75DP130).

They have tested their whole product with 0°C environment at chamber and there is link training issue.

When customer has read the DPCD register TRAINING_LANE_SET at 0°C  will be different with room temperature.

And, it will induce the DP signal transfer fail from host to device side.

They also has tested with previous design with our SN75DP130 with the same host and  device but it doesn't show this behavior.

It can light up the monitor normally.

Do you have any direction to debug it? We have suspected the problem of layout . Do you think it will induce this kind of failure at  0°C?

Please use the below link to download the schematic & layout. 

https://txn.box.com/s/iw23wkxel7zzv9mpw8q4jazexmxt1wfx

Thanks.

  • 0
    TI__Guru**** 178126 points

    The link to the schematic/layout appears to be broken, would you please re-send the link?

    When customer has read the DPCD register TRAINING_LANE_SET at 0°C  will be different with room temperature.

    What is the SWING and Pre-emphasis setting for the room temperature and what is the SWING and Pre-emphasis setting for the 0C? Are they basically seeing the link training fail with max SWING and Pre-emphasis? If so, does the link training pass if they switch to a shorter cable?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    TI__Expert 8790 points

    Hi David,

    From my memory, their result is as below. Also asking the exact value of it from customer. 

    SWING and Pre-emphasis setting for the room temperature : level 2 15db

    SWING and Pre-emphasis setting for the 0C: level 0 0db

    Sorry. Could you try the below link directly? I think there is some issue at the hyperlink of e2e. Thanks.

    txn.box.com/.../iw23wkxel7zzv9mpw8q4jazexmxt1wfx

    Thanks.

  • 0 in reply to Feng bin Su
    TI__Guru**** 178126 points

    From the schematic, the DP130 is in the AUX snoop mode, it is not passing the AUX traffic between the source and the sink. Do they have a AUX monitor that can monitor the AUX traffic between the source and the sink? 

    If SWING and Pre-emphasis setting for the 0C is level 0, the question is whether the sink only requested level 0 or the sink requested a level other than level 0, but the DP130 is not properly decoding the AUX traffic. We can answer this question when we look at the AUX traffic.

    When they cool the temperature down to 0C, do they only cool the DP130 or the entire board? When they cool the temperature down to 0C, have they tried to unplug/plug the cable again?

    Thanks

    David